Move LimitedThreadBundleWrapper to vespalib.

3 files changed, 56 insertions, 0 deletions

diff --git a/vespalib/src/vespa/vespalib/util/CMakeLists.txt b/vespalib/src/vespa/vespalib/util/CMakeLists.txt
index 79000a89f5f..406ea68a08a 100644
--- a/vespalib/src/vespa/vespalib/util/CMakeLists.txt
+++ b/vespalib/src/vespa/vespalib/util/CMakeLists.txt
@@ -49,6 +49,7 @@ vespa_add_library(vespalib_vespalib_util OBJECT
     jsonwriter.cpp
     latch.cpp
     left_right_heap.cpp
+    limited_thread_bundle_wrapper.cpp
     lz4compressor.cpp
     malloc_mmap_guard.cpp
     md5.c
diff --git a/vespalib/src/vespa/vespalib/util/limited_thread_bundle_wrapper.cpp b/vespalib/src/vespa/vespalib/util/limited_thread_bundle_wrapper.cpp
new file mode 100644
index 00000000000..15a5bf101f0
--- /dev/null
+++ b/vespalib/src/vespa/vespalib/util/limited_thread_bundle_wrapper.cpp
@@ -0,0 +1,31 @@
+// Copyright Vespa.ai. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
+
+#include "limited_thread_bundle_wrapper.h"
+#include "exceptions.h"
+
+namespace vespalib {
+
+LimitedThreadBundleWrapper::LimitedThreadBundleWrapper(ThreadBundle& thread_bundle, uint32_t max_threads)
+    : _thread_bundle(thread_bundle),
+      _max_threads(std::min(max_threads, static_cast<uint32_t>(thread_bundle.size())))
+{
+}
+
+LimitedThreadBundleWrapper::~LimitedThreadBundleWrapper() = default;
+
+size_t
+LimitedThreadBundleWrapper::size() const
+{
+    return _max_threads;
+}
+
+void
+LimitedThreadBundleWrapper::run(Runnable* const* targets, size_t cnt)
+{
+    if (cnt > size()) {
+        throw IllegalArgumentException("too many targets");
+    }
+    _thread_bundle.run(targets, cnt);
+}
+
+}
diff --git a/vespalib/src/vespa/vespalib/util/limited_thread_bundle_wrapper.h b/vespalib/src/vespa/vespalib/util/limited_thread_bundle_wrapper.h
new file mode 100644
index 00000000000..de3c58bf74d
--- /dev/null
+++ b/vespalib/src/vespa/vespalib/util/limited_thread_bundle_wrapper.h
@@ -0,0 +1,24 @@
+// Copyright Vespa.ai. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
+
+#pragma once
+
+#include "thread_bundle.h"
+
+namespace vespalib {
+
+/*
+ * A ThreadBundle implementation that limits the number of available threads
+ * from the backing thread bundle.
+ */
+class LimitedThreadBundleWrapper : public ThreadBundle
+{
+    ThreadBundle&  _thread_bundle;
+    const uint32_t _max_threads;
+public:
+    LimitedThreadBundleWrapper(ThreadBundle& thread_bundle, uint32_t max_threadss);
+    ~LimitedThreadBundleWrapper() override;
+    size_t size() const override;
+    void run(Runnable* const* targets, size_t cnt) override;
+};
+
+}